This invention relates generally to a cardiograph of the type used to provide a record of data from conventional electrocardiograph sensors which are applied to a patient's body and more particularly to a small, hand held, battery powered miniature phono- and electrocardiograph which may be conveniently carried by doctors, nurses, interns, technicians and emergency service personnel. Conventional EKG machines are used under controlled conditions wherein the patient is carefully prepared for the measurements which are to be made. The machines are generally bulky and expensive and for both reasons are not considered portable such that a doctor would transport them in his normal rounds, nor would these instruments be practical for transport by nurses, technicians and the like. Thus the use of EKG machines has been limited although the permanent record which these machines provide of a patients condition at a given moment of time is an invaluable tool to the practioner.
Another disadvantage of conventional machines outputting a cardiogram is the size and delicateness of the printer which is required to produce a substantially instantaneous analog representation of the EKG signals as they are detected. The ability of the recording pen to accurately follow the inputted electrical driving signals leaves room for improvement and the use of an oscilloscope, while accurately following the electrical signals, provides no permanent record unless supplementary equipment for photographic recording is provided. Thus the complexity of such devices is compounded and portability enabling on-site utility is further limited.
Further, it would be medically useful to provide a permanent record of a signal representative of the audible output of a stethoscope, so as to provide a permanent record, and to permit comparison with an electrocardiogram of the patient.
What is needed is a miniature phono- and electrocardiograph which is small, lightweight and therefore portable, and provides an accurate, permanent record of EKG and phono inputs as from a stethoscope.